I'd have to agree with Cactus on this...
1) Either you can weld or you can't .... 100% Right On!!!
2) Most of the "BIG" jobs I've been on, (refineries, powerplants) except for a couple where the "alloy pipewelders" had 3 or more certs, the person welding Uni-strut for the "Sparkies" made the same as the B31.1 and B31.3 pipe welders.
3) and finally, When I ran a rig truck, the rate was the same for "red iron" as it was for pipe.
Stories of the Alaska Pipeline and Americans going abroad in the 50's and 60's of fortunes made in the Middle East still circulate.
In a way, the "PipeDream" of fortunes to be made being a pipeliner or rig welder embodies the American Dream. Starting your own business, being independent, travelling across the country is somewhat analogous to the 1849 Gold Rush. It is this adventurous spirit and the resultant success stories that made America what it is and keeps the "Dream Alive"!
Hell, I wanna be a Pipeliner when I grow up!